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Regional co-variability of spatial and temporal soil moisture-precipitation coupling in North Africa : an observational perspective

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Abstract
The magnitude and sign of soil moisture-precipitation coupling (SMPC) is investigated using a probability-based approach and 10 years of daily microwave satellite data across North Africa at a 1 degrees horizontal scale. Specifically, the co-existence and co-variability of spatial (i.e. using soil moisture gradients) and temporal (i.e. using soil moisture anomaly) soil moisture effects on afternoon rainfall is explored. The analysis shows that in the semi-arid environment of the Sahel, the negative spatial and the negative temporal coupling relationships do not only co-exist, but are also dependent on one another. Hence, if afternoon rain falls over temporally drier soils, it is likely to be surrounded by a wetter environment. Two regions are identified as SMPC "hot spots". These are the south-western part of the domain (7-15 degrees N, 10 degrees W-7 degrees E), with the most robust negative SMPC signal, and the South Sudanese region (5-13 degrees N, 24-34 degrees E). The sign and significance of the coupling in the latter region is found to be largely modulated by the presence of wetlands and is susceptible to the number of long-lived propagating convective systems. The presence of wetlands and an irrigated land area is found to account for about 30% of strong and significant spatial SMPC in the North African domain. This study provides the first insight into regional variability of SMPC in North Africa, and supports the potential relevance of mechanisms associated with enhanced sensible heat flux and mesoscale variability in surface soil moisture for deep convection development.
Keywords
MESOSCALE CONVECTIVE SYSTEM, BOUNDARY LAYER INTERACTIONS, WEST-AFRICA, ATMOSPHERIC CONTROLS, RELATIVE-HUMIDITY, AMMA CAMPAIGN, LARGE-SCALE, LIFE-CYCLE, FEEDBACK, RAINFALL

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MLA
Petrova, Irina, et al. “Regional Co-Variability of Spatial and Temporal Soil Moisture-Precipitation Coupling in North Africa : An Observational Perspective.” HYDROLOGY AND EARTH SYSTEM SCIENCES, vol. 22, no. 6, 2018, pp. 3275–94, doi:10.5194/hess-2017-530.
APA
Petrova, I., van Heerwaarden, C. C., Hohenegger, C., & Guichard, F. (2018). Regional co-variability of spatial and temporal soil moisture-precipitation coupling in North Africa : an observational perspective. HYDROLOGY AND EARTH SYSTEM SCIENCES, 22(6), 3275–3294. https://doi.org/10.5194/hess-2017-530
Chicago author-date
Petrova, Irina, Chiel C. van Heerwaarden, Cathy Hohenegger, and Françoise Guichard. 2018. “Regional Co-Variability of Spatial and Temporal Soil Moisture-Precipitation Coupling in North Africa : An Observational Perspective.” HYDROLOGY AND EARTH SYSTEM SCIENCES 22 (6): 3275–94. https://doi.org/10.5194/hess-2017-530.
Chicago author-date (all authors)
Petrova, Irina, Chiel C. van Heerwaarden, Cathy Hohenegger, and Françoise Guichard. 2018. “Regional Co-Variability of Spatial and Temporal Soil Moisture-Precipitation Coupling in North Africa : An Observational Perspective.” HYDROLOGY AND EARTH SYSTEM SCIENCES 22 (6): 3275–3294. doi:10.5194/hess-2017-530.
Vancouver
1.
Petrova I, van Heerwaarden CC, Hohenegger C, Guichard F. Regional co-variability of spatial and temporal soil moisture-precipitation coupling in North Africa : an observational perspective. HYDROLOGY AND EARTH SYSTEM SCIENCES. 2018;22(6):3275–94.
IEEE
[1]
I. Petrova, C. C. van Heerwaarden, C. Hohenegger, and F. Guichard, “Regional co-variability of spatial and temporal soil moisture-precipitation coupling in North Africa : an observational perspective,” HYDROLOGY AND EARTH SYSTEM SCIENCES, vol. 22, no. 6, pp. 3275–3294, 2018.
@article{8532224,
  abstract     = {{The magnitude and sign of soil moisture-precipitation coupling (SMPC) is investigated using a probability-based approach and 10 years of daily microwave satellite data across North Africa at a 1 degrees horizontal scale. Specifically, the co-existence and co-variability of spatial (i.e. using soil moisture gradients) and temporal (i.e. using soil moisture anomaly) soil moisture effects on afternoon rainfall is explored. The analysis shows that in the semi-arid environment of the Sahel, the negative spatial and the negative temporal coupling relationships do not only co-exist, but are also dependent on one another. Hence, if afternoon rain falls over temporally drier soils, it is likely to be surrounded by a wetter environment. Two regions are identified as SMPC "hot spots". These are the south-western part of the domain (7-15 degrees N, 10 degrees W-7 degrees E), with the most robust negative SMPC signal, and the South Sudanese region (5-13 degrees N, 24-34 degrees E). The sign and significance of the coupling in the latter region is found to be largely modulated by the presence of wetlands and is susceptible to the number of long-lived propagating convective systems. The presence of wetlands and an irrigated land area is found to account for about 30% of strong and significant spatial SMPC in the North African domain. This study provides the first insight into regional variability of SMPC in North Africa, and supports the potential relevance of mechanisms associated with enhanced sensible heat flux and mesoscale variability in surface soil moisture for deep convection development.}},
  author       = {{Petrova, Irina and van Heerwaarden, Chiel C. and Hohenegger, Cathy and Guichard, Françoise}},
  issn         = {{1027-5606}},
  journal      = {{HYDROLOGY AND EARTH SYSTEM SCIENCES}},
  keywords     = {{MESOSCALE CONVECTIVE SYSTEM,BOUNDARY LAYER INTERACTIONS,WEST-AFRICA,ATMOSPHERIC CONTROLS,RELATIVE-HUMIDITY,AMMA CAMPAIGN,LARGE-SCALE,LIFE-CYCLE,FEEDBACK,RAINFALL}},
  language     = {{eng}},
  number       = {{6}},
  pages        = {{3275--3294}},
  title        = {{Regional co-variability of spatial and temporal soil moisture-precipitation coupling in North Africa : an observational perspective}},
  url          = {{http://doi.org/10.5194/hess-2017-530}},
  volume       = {{22}},
  year         = {{2018}},
}

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